lavas of, 384.

Torrents, action of, in widening valleys, 204.

Torres' Strait, volcano of, 792.

Totten, Col., on expansion of rocks by heat, 562.

Tournal, M., on French caves, 738, 739.

Towns destroyed by landslips, 732.

Trade-winds, 106, 295.

Traditions of losses of land, 324, 327.
----, of floods, 500, 501.

Transition texture, 176.
----, formations, 177.

Trap rocks of many different ages, 160.

Travertin of the Elsa, 239.
----, of San Vignone, 240.
----, of San Filippo, 241.
----, spheroidal structure of, 242.
----, compared to English magnesian limestone, 243.
----, of Tivoli, 244.

Travertin politic, recent, in Lancerote, 439.

Tree-ferns, distribution of, 88.

Tree-ferns, extend more south than north of equator, 86.

Trees, longevity of, 422.

Trias, fossil mammifer of, 137.

Trimmer, Mr., on recent marine shells in Wales, 122.

Trinidad, subsidence in, 250.
----, pitch lake of, 250.

Tripergola, 370, 371, 395.

Tripolitza, plain of, breccias in, 734.

Trollhattan, 527.

Truncation of volcanic cones, 352, 493.

Tufa. _See_ Travertin.

Tuff, infusorial, 388.

Turner, Dr., on decomposition of felspar, 247.

Turtles, migrations of, 645.
----, eggs of, fossil, 771.

Turton cited, 646.

Tuscany, geology of, 23, 40.
----, calcareous springs of, 239.

Tyrol, Dolomieu on the, 49.

U.

Uddevalla, upraised deposits at, 184, 527.

Uliah Bund, formation of the, 462.

Ulloa cited, 501, 502, 685.

Unconformable strata, inferences derived from, 187.

Uniformity of laws of nature, 71, 149, 373.
----, of system of past changes in animate and inanimate world, 181.

Universal formations, theory of, 49, 154.

Universal ocean, theory of, 26, 34.
----, disproved by organic remains, 191.

Upsala, strata near, 528.

V.

Val d'Arno, Upper, effect of destruction of forests in, 712.

Val del Bove on Etna described, 403.
----, form, composition, and origin of dikes in, 406.
----, lavas and breccias of the, 411.
----, origin of the, 413.
----, floods in, 411.

Val di Calanna, 405, 407, 410.

Val di Noto, Dolomieu on the, 49.

Valdivia, earthquake at, 453.

Valenciennes, M., on fish not crossing the Atlantic, 647.

Valley, newly formed in Georgia, U. S., 205.

Valleys, Targioni on origin of, 40.
----, excavation of, in Central France, 213